Pontrhyn Bridge crosses the Taff at Troedyrhiw, and is believed to be located on the site of an ancient bridge that dates back at least 500 years. Legend claims that the bridge was the site where Rhun, the son of a local chieftain and brother of Tydfil (from whom the name Merthyr Tydfil is said to derive), was killed defending the area from marauding Picts in the 5th Century.

Up until the 19th century this area was rural and agricultural. In 1771 a map shows that Troedyrhiw was comprised of a large farm, a corn mill and just three other buildings.

The Merthyr and Cardiff Guardian, in 1852, observed the changes that took place at Troedyrhiw during the 19th century:

"This place bids to be a star of the first magnitude. It formerly only had a chapel, two taverns, a few cottages, an engine-house, the remnant of a mill, and a miserable shed...speculative spirit…has led to the erection of numerous cottages, by perpetual battering, the Taff Vale Railway has been induced to improve their station; and the place has been successfully adorned with Villas, a new church and two or three new meeting houses...nearly all the houses have been built under the sanction of the board of Health, and are really what human habitation ought to be."

Castle Pit

Sunk by the Crawshay family in the 1866, Castle Pit was located in the centre of Troedyrhiw. The colliery was opened expressly to mine steam coal and sell it commercially.

As the iron industry became more erratic collieries like Castle were opened and ironmasters entered 'the sale coal market' to subsidise their failing ironworks. Overtime however, the collieries totally replaced the ironworks as the main trade in the Merthyr area.

The single shaft at Castle reached a depth of over 400metres to mine the excellent quality seams on the west side of the Taff.

Church of St John the Baptist

The parish Church of St John the Baptist was built in 1853 by Anthony Hill, ironmaster of the nearby Plymouth Works. The church was built by Anthony on condition that he would be the only person to be buried in the church grounds. He is said to be buried in an iron coffin. When he died the workmen were given the day off to attend his funeral, with full pay, but out of respect for him they each donated their days pay to purchase the stained glass window on the east side of the church.